single.rb in bindata-0.9.0

- old
+ new

@@ -4,10 +4,30 @@
   # A BinData::Single object is a container for a value that has a particular
   # binary representation.  A value corresponds to a primitive type such as
   # as integer, float or string.  Only one value can be contained by this
   # object.  This value can be read from or written to an IO stream.
   #
+  #   require 'bindata'
+  #
+  #   obj = BinData::Uint8.new(:initial_value => 42)
+  #   obj.value #=> 42
+  #   obj.value = 5
+  #   obj.value #=> 5
+  #   obj.clear
+  #   obj.value #=> 42
+  #
+  #   obj = BinData::Uint8.new(:value => 42)
+  #   obj.value #=> 42
+  #   obj.value = 5
+  #   obj.value #=> 42
+  #
+  #   obj = BinData::Uint8.new(:check_value => 3)
+  #   obj.read("\005") #=> BinData::ValidityError: value is '5' but expected '3'
+  #
+  #   obj = BinData::Uint8.new(:check_value => lambda { value < 5 })
+  #   obj.read("\007") #=> BinData::ValidityError: value not as expected
+  #
   # == Parameters
   #
   # Parameters may be provided at initialisation to control the behaviour of
   # an object.  These params include those for BinData::Base as well as:
   #
@@ -26,19 +46,19 @@
   #                           or failure.  Any other return is compared to
   #                           the value just read in.
   class Single < Base
     # These are the parameters used by this class.
     optional_parameters :initial_value, :value, :check_value
+    mutually_exclusive_parameters :initial_value, :value
 
-    # Register the names of all subclasses of this class.
-    def self.inherited(subclass) #:nodoc:
-      register(subclass.name, subclass)
+    # Single objects don't contain fields so this returns an empty list.
+    def self.all_possible_field_names(sanitized_params)
+      []
     end
 
     def initialize(params = {}, env = nil)
       super(params, env)
-      ensure_mutual_exclusion(:initial_value, :value)
       clear
     end
 
     # Resets the internal state to that of a newly created object.
     def clear
@@ -88,10 +108,15 @@
     # Returns a snapshot of this data object.
     def snapshot
       value
     end
 
+    # Single objects are single_values
+    def single_value?
+      true
+    end
+
     # Single objects don't contain fields so this returns an empty list.
     def field_names
       []
     end
 
@@ -147,11 +172,11 @@
       raise EOFError, "End of file reached" if str == nil
       raise IOError, "data truncated" if str.size < n
       str
     end
 
-=begin
+    ###########################################################################
     # To be implemented by subclasses
 
     # Return the string representation that +val+ will take when written.
     def val_to_str(val)
       raise NotImplementedError
@@ -166,8 +191,8 @@
     def sensible_default
       raise NotImplementedError
     end
 
     # To be implemented by subclasses
-=end
+    ###########################################################################
   end
 end